Android 数据不存在';未在recyclerview上显示-出现错误,未连接布局管理器;跳过布局
我试图从Firebase实时数据库检索数据到Recycler视图。我已经创建了名为Ph.java的Modul类和名为PhAdapter.java的适配器。但是,我对调用MainActivity.java上的适配器感到非常困惑。这是我的代码:) 博士班Android 数据不存在';未在recyclerview上显示-出现错误,未连接布局管理器;跳过布局,android,android-recyclerview,Android,Android Recyclerview,我试图从Firebase实时数据库检索数据到Recycler视图。我已经创建了名为Ph.java的Modul类和名为PhAdapter.java的适配器。但是,我对调用MainActivity.java上的适配器感到非常困惑。这是我的代码:) 博士班 public class Ph { public String date; public String nilai; public String time; public Ph(){ } pub
public class Ph {
public String date;
public String nilai;
public String time;
public Ph(){
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
public String getNilai() {
return nilai;
}
public void setNilai(String nilai) {
this.nilai = nilai;
}
public String getTime() {
return time;
}
public void setTime(String time) {
this.time = time;
}
}
这是我的PhAdapter.java
public class PhAdapter extends RecyclerView.Adapter<PhAdapter.PhViewHolder> {
private List<Ph> dataph;
private Context context;
public PhAdapter(List<Ph> dataph, Context context) {
this.dataph = dataph;
this.context = context;
}
@Override
public PhViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
//View view = LayoutInflater.from(parent.getContext()).inflate(rowLayout, parent, false);
View view = LayoutInflater.from(context).inflate(R.layout.view_ph_list,parent,false);
PhViewHolder phViewHolder = new PhViewHolder(view);
return new PhViewHolder(view);
}
@Override
public void onBindViewHolder(final PhViewHolder holder, final int position) {
Ph mylist = dataph.get(position);
holder.tvNilai.setText(mylist.getNilai());
holder.tvTime.setText(mylist.getTime());
holder.tvDate.setText(mylist.getDate());
}
@Override
public int getItemCount() {
int arr = 0;
try{
if(dataph.size()==0){
arr = 0;
}
else{
arr=dataph.size();
}
}catch (Exception e){
}
return arr;
}
public static class PhViewHolder extends RecyclerView.ViewHolder {
private TextView tvNilai, tvDate, tvTime;
public PhViewHolder(View itemview) {
super(itemview);
tvNilai = (TextView) itemview.findViewById(R.id.tv_ph);
tvTime = (TextView) itemview.findViewById(R.id.tv_time);
tvDate = (TextView) itemview.findViewById(R.id.tv_date);
}
}
}
公共类PhAdapter扩展了RecyclerView.Adapter{
私有列表数据;
私人语境;
公共PhAdapter(列表数据、上下文){
this.dataph=dataph;
this.context=上下文;
}
@凌驾
公共PhViewHolder onCreateViewHolder(视图组父级,int-viewType){
//View=LayoutInflater.from(parent.getContext()).flate(rowLayout,parent,false);
视图=布局更平坦。从(上下文)。充气(R.layout.View\u ph\u列表,父项,false);
PhViewHolder PhViewHolder=新PhViewHolder(视图);
返回新的PhViewHolder(视图);
}
@凌驾
公共无效onBindViewHolder(最终PhViewHolder,最终int位置){
Ph mylist=dataph.get(位置);
holder.tvNilai.setText(mylist.getNilai());
holder.tvTime.setText(mylist.getTime());
holder.tvDate.setText(mylist.getDate());
}
@凌驾
public int getItemCount(){
int-arr=0;
试一试{
如果(dataph.size()==0){
arr=0;
}
否则{
arr=dataph.size();
}
}捕获(例外e){
}
返回arr;
}
公共静态类PhViewHolder扩展了RecyclerView.ViewHolder{
私有文本视图tvNilai、tvDate、tvTime;
公共PhViewHolder(查看项目视图){
超级(项目视图);
tvNilai=(TextView)itemview.findViewById(R.id.tv_ph);
tvTime=(TextView)itemview.findViewById(R.id.tv_time);
tvDate=(TextView)itemview.findViewById(R.id.tv_date);
}
}
}
还有我的主要活动课
public class MainActivity extends AppCompatActivity {
FirebaseDatabase database;
DatabaseReference myRef;
List<Ph> dataph;
RecyclerView recyclerView;
Button cekdata;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
cekdata = (Button) findViewById(R.id.btn_cekdata);
recyclerView = (RecyclerView) findViewById(R.id.recycler_view1);
database = FirebaseDatabase.getInstance();
myRef = database.getReference("ph");
myRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
dataph = new ArrayList<Ph>();
for (DataSnapshot dataSnapshot1 :dataSnapshot.getChildren()){
Ph value = dataSnapshot1.getValue(Ph.class);
Ph phModel = new Ph();
String tvNilai = value.getNilai();
String tvDate = value.getDate();
String tvTime = value.getTime();
phModel.setNilai(tvNilai);
phModel.setDate(tvDate);
phModel.setTime(tvTime);
dataph.add(phModel);
}
}
@Override
public void onCancelled(DatabaseError databaseError) {
//Failed to read value
Log.w("Hello", "Failed to read Ph.", databaseError.toException());
}
});
cekdata.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
PhAdapter phAdapter = new PhAdapter(dataph,MainActivity.this);
RecyclerView.LayoutManager recyce = new LinearLayoutManager(MainActivity.this);
recyclerView.setLayoutManager(recyce);
recyclerView.setAdapter(phAdapter);
}
});
}
}
public类MainActivity扩展了AppCompatActivity{
Firebase数据库;
数据库参考myRef;
列出数据库;
回收视图回收视图;
按钮cekdata;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
cekdata=(按钮)findviewbyd(R.id.btn_cekdata);
recyclerView=(recyclerView)findViewById(R.id.recycler\u视图1);
database=FirebaseDatabase.getInstance();
myRef=database.getReference(“ph”);
myRef.addValueEventListener(新的ValueEventListener(){
@凌驾
公共void onDataChange(DataSnapshot DataSnapshot){
dataph=新的ArrayList();
对于(DataSnapshot dataSnapshot1:DataSnapshot.getChildren()){
Ph值=dataSnapshot1.getValue(Ph.class);
Ph phModel=新Ph();
字符串tvNilai=value.getNilai();
字符串tvDate=value.getDate();
字符串tvTime=value.getTime();
phModel.setNilai(tvinlai);
phModel.setDate(tvDate);
phModel.setTime(tvTime);
dataph.add(phModel);
}
}
@凌驾
已取消的公共void(DatabaseError DatabaseError){
//无法读取值
Log.w(“Hello”,“读取Ph.失败”,databaseError.toException());
}
});
setOnClickListener(新视图.OnClickListener(){
@凌驾
公共void onClick(视图){
PhAdapter PhAdapter=新PhAdapter(dataph,MainActivity.this);
RecycleView.LayoutManager recyce=新的LinearLayoutManager(MainActivity.this);
recyclerView.setLayoutManager(recyce);
recyclerView.setAdapter(phAdapter);
}
});
}
}
当我点击按钮时,数据没有显示在recyclerview上,我得到了一个错误,recyclerview:No layout manager attached;跳过布局。您需要完全初始化LinearLayoutManager,如下所示:
recyclerView = (RecyclerView) findViewById(R.id.recycler_view1);
RecyclerView.LayoutManager recyce = new
LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false);
recyclerView.setLayoutManager(recyce);
PhAdapter phAdapter = new PhAdapter(dataph,MainActivity.this);
recyclerView.setAdapter(phAdapter);
更正后的活动类应如下所示:
public class MainActivity extends AppCompatActivity {
FirebaseDatabase database;
DatabaseReference myRef;
List<Ph> dataph= new ArrayList<>();
RecyclerView recyclerView;
PhAdapter phAdapter;
Button cekdata;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
cekdata = (Button) findViewById(R.id.btn_cekdata);
recyclerView = (RecyclerView) findViewById(R.id.recycler_view1);
RecyclerView.LayoutManager recyce = new LinearLayoutManager(this,LinearLayoutManager.VERTICAL,false);
recyclerView.setLayoutManager(recyce);
phAdapter = new PhAdapter(dataph,MainActivity.this);
recyclerView.setAdapter(phAdapter);
database = FirebaseDatabase.getInstance();
myRef = database.getReference("ph");
myRef.addValueEventListener(new ValueEventListener() {
@Override
public void onDataChange(DataSnapshot dataSnapshot) {
for (DataSnapshot dataSnapshot1 :dataSnapshot.getChildren()){
Ph value = dataSnapshot1.getValue(Ph.class);
Ph phModel = new Ph();
String tvNilai = value.getNilai();
String tvDate = value.getDate();
String tvTime = value.getTime();
phModel.setNilai(tvNilai);
phModel.setDate(tvDate);
phModel.setTime(tvTime);
dataph.add(phModel);
}
phAdapter.notifyDataSetChanged();
}
@Override
public void onCancelled(DatabaseError databaseError) {
//Failed to read value
Log.w("Hello", "Failed to read Ph.", databaseError.toException());
}
});
cekdata.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View view) {
phAdapter.notifyDataSetChanged();
}
});
}
}
public类MainActivity扩展了AppCompatActivity{
Firebase数据库;
数据库参考myRef;
List dataph=new ArrayList();
回收视图回收视图;
PhAdapter PhAdapter;
按钮cekdata;
@凌驾
创建时受保护的void(Bundle savedInstanceState){
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
cekdata=(按钮)findviewbyd(R.id.btn_cekdata);
recyclerView=(recyclerView)findViewById(R.id.recycler\u视图1);
RecyclerView.LayoutManager recyce=新的LinearLayoutManager(这是LinearLayoutManager.VERTICAL,false);
recyclerView.setLayoutManager(recyce);
phAdapter=新的phAdapter(dataph,MainActivity.this);
recyclerView.setAdapter(phAdapter);
database=FirebaseDatabase.getInstance();
myRef=database.getReference(“ph”);
myRef.addValueEventListener(新的ValueEventListener(){
@凌驾
公共void onDataChange(DataSnapshot DataSnapshot){
对于(DataSnapshot dataSnapshot1:DataSnapshot.getChildren()){
Ph值=dataSnapshot1.getValue(Ph.class);
Ph phModel=新Ph();
字符串tvNilai=value.getNilai();
字符串tvDate=value.getDate();
字符串tvTime=value.getTime();
phModel.setNilai(tvinlai);
phModel.setDate(tvDate);
phModel.setTime(tvTime);
dataph.add(phModel);
}
phAdapter.notifyDataSetChanged();
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.setLayoutManager(new LinearLayoutManager(this));
recyclerView.layoutManager = LinearLayoutManager(this)
<android.support.v7.widget.RecyclerView
android:id="@+id/recyclerView"
android:layout_width="match_parent"
android:layout_height="match_parent"
app:layoutManager="android.support.v7.widget.LinearLayoutManager"
/>